REPOET ON THE ASTEROIDEA. 63 



1. Dijtaster spinostis, n. sp. (PL V. figs. 1 and 2; PL IV. figs. 11 and 12). 



Rays five. K = 1G0-164 mm. ; r = 30 mm. R > 5 r. Breadth of a ray near the 

 base (between the second and third supero-marginal plates), 22 mm. 



Eays tolerably elongate, robust, and tapering, more or less depressed, with the lateral 

 walls angularly rounded. Interbrachial arcs wide and openly rounded. Disk compara- 

 tively large and massive. Abactinal area of disk slightly inflated, especially opposite the 

 base of the rays, the inflation being continued for a short distance along the abactinal 

 surface of the ray, which is at first regularly convex, but becomes flat before half the 

 length is attained, and continues so up to the extremity. Actinal surface of the disk 

 prominent at the mouth - angles and sloping thence to the margin ; that of the rays 

 slightly convex, giving them more or less of a rounded appearance when viewed from 

 below. 



The abactinal surface of the disk and rays is covered with small closely crowded paxillae, 

 composed of short, cylindrical, papilliform, obtusely tipped, equal-sized spinelets, seven to 

 ten in each. Paxillse with fewer spinelets are interspersed amongst the large ones ; and 

 on the outer half of the ray seldom more than three to five spinelets occur, and these are 

 reduced to mere papilliform granules. The spinelets in the paxillse upon the disk and 

 inner half of the rays stand nearly perpendicular, in little brush - like groups, but are 

 so closely crowded in this region that it is often impossible to distinguish the individual 

 paxillae. No pedicellarire are present. 



The supero-marginal plates, forty-two to forty-four in number from the median interradial 

 line to the extremity, are wholly visible when the starfish is viewed from above. They 

 form a broad, sloping, or bevelled border to the abactinal surface, and even a portion of the 

 infero-marginal plates is also visible ; the latter forming exclusively the outline of the 

 ray. The supero-marginal plates are rectangular, with the length greater than the height, 

 excepting a few plates in the interbrachial arc, in which the dimensions are subequal. On 

 the outer part of the ray the height is more than half the length. Each plate bears on its 

 upper margin a short and comparatively delicate, straight, cylindrical, tapering, sharply 

 pointed spine, the longest about 3*5 mm. in length, and they decrease very slightly as 

 they proceed along the ray. The spines are directed upwards and at an angle of about 

 45° towards the extremity. Earely some plates bear two spines, one generally smaller 

 than the other. The surface of the plate is covered with small, uniform, papilliform 

 granules, rather widely spaced on the middle of the plate, but becoming crowded and more 

 elongate at the adoral and aboral margins. 



The infero-marginal plates correspond to the superior series, their line of union being 

 perfectly horizontal. These plates have their surface curved, so that a portion is visible 

 when the starfish is viewed from above, and they form entirely the outer margin of the 

 ray. Indeed, beyond the middle of the ray their extent upon the abactinal area is nearly 

 as great as on the actinal, and the rounding is slightly angular. Each plate bears on the 



